Preamp with tone control

Rodeodave · 7th February 2006, 09:37 AM

Hi,

Maybe this is not considered high-end, but neither my speaker(s) nor my room has a flat frequency-response.
And sometimes some tracks need more base/mid/treble, whatever.

Well...I've tried to "design" an unbalanced preamp with built-in tone control. (-> differential pair, tone control, mixing stage)

I didn't want to use inductors, so I've tried to gyrate capacitors (=transforming capacitance into inductance, inversely proportional) using FETs.
It's possible to gyrate a capacitor using tubes or op-amps. To keep up the spirit, I want to use FETs, but I don't want to diy op-amps directly (too many parts).

Simulating it with circuitmaker indicated that some of my part's values are wrong. There's no effect on the signal, I think because the FETs in the gyrating stage are not turned on. And there's no gain.

The idea is to use the balanced zen pre as a differential pair, tone control with gyrated caps instead of inductors and a simple mixing stage (mixing the pure signal with the tweaked signal).

Maybe someone can help me fix the circuit.

Yarr, Dave

Nelson Pass · 7th February 2006, 07:04 PM

Here's an old one I used from 1974 which may help you.

hifimaker · 7th February 2006, 08:48 PM

Tone controls?? That's Sacrilege!

Egads... more stuff in the signal path.

-David

wchick · 7th February 2006, 11:05 PM

I think if you cannot make the sound in good tonal balance, you will never listen to "music".

WC

Rodeodave · 8th February 2006, 03:50 PM

Yep, it's Sacrilege. And there are more parts to the signal path, I agree.

But sometimes I just can't cope with how some tracks are mixed. Some old Beastie Boys records need more base (esp. License to ill), some recordings of Dvorak (Nr.9) are, for my taste and on my system, a bit flat in the mids, Aphex Twin loves the highs,...

I want simple tone controls, embedded in a pre-amp. That is it.

Mr. Pass,

I can't figure out the value of the middle cap, is that 3µF? And the bypass cap (at the transitor), is that 10µF?! And what kind of transistor should I use, maybe a TIP... or MPSA..., or can i use an n-chanel FET?

Thanks a lot, Dave

Bob Richards · 12th June 2011, 07:22 PM

Anyone who buys in to that malarky that tone controls are bad, is a sucker.

8th February 2006, 03:50 PM	#5
Rodeodave diyAudio Member Join Date: Dec 2004 Location: in the alps Blog Entries: 1	Yep, it's Sacrilege. And there are more parts to the signal path, I agree. But sometimes I just can't cope with how some tracks are mixed. Some old Beastie Boys records need more base (esp. License to ill), some recordings of Dvorak (Nr.9) are, for my taste and on my system, a bit flat in the mids, Aphex Twin loves the highs,... I want simple tone controls, embedded in a pre-amp. That is it. Mr. Pass, I can't figure out the value of the middle cap, is that 3µF? And the bypass cap (at the transitor), is that 10µF?! And what kind of transistor should I use, maybe a TIP... or MPSA..., or can i use an n-chanel FET? Thanks a lot, Dave __________________ Gravity - Making the G since 13.7 billion B.C.

Thread Tools	Search this Thread
Show Printable Version Email this Page	Search this Thread: Advanced Search

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
My active preamp/tone-control and TL074	kaushama	Chip Amps	27	13th June 2011 01:54 PM
Tube preamp, tone control problem	Ahmad_tbp	Tubes / Valves	17	9th March 2011 11:56 PM
i need preamp schematics w/o tone control or volume control	hernanstafe	Parts	7	30th January 2008 03:12 AM
TI's Tone control	JhonDoe	Chip Amps	26	13th July 2004 01:29 AM

New To Site?	Need Help?
Register to Participate Search Privacy Statement Contact Us	Frequently Asked Questions Did you forget your password? Mark Forums Read


	Please consider donating to help us continue to serve you. Ads on/off / Custom Title / More PMs / More album space / Advanced printing & mass image saving

7th February 2006, 08:48 PM	#3
hifimaker diyAudio Member Join Date: Oct 2003 Location: San Jose	Tone controls?? That's Sacrilege! Egads... more stuff in the signal path. -David

7th February 2006, 11:05 PM	#4
wchick diyAudio Member Join Date: Jul 2002 Location: Colorado	I think if you cannot make the sound in good tonal balance, you will never listen to "music". WC

12th June 2011, 07:22 PM	#6
Bob Richards diyAudio Member Join Date: Feb 2011 Location: Portland Oregon, USA	Anyone who buys in to that malarky that tone controls are bad, is a sucker.